<volist name="tree" id="info">
    <li>
        <a class="J_menuItem" <empty name="info._">href="{:U('Article/index',['category_id'=>$info['id']])}"</empty> style="overflow: hidden;white-space: nowrap;text-overflow: ellipsis;">{$info.title}
            <notempty name="info._">
                <span class="fa arrow" style="position: absolute; right: 10px;"></span>
            </notempty>
        </a>
        <notempty name="info._">
            <ul class="nav nav-second-level" style="padding-left: 10px;">
                {:R('Index/category_tree', array($info['_']))}
            </ul>
        </notempty>
    </li>
</volist>